My foundation is Tae Kwon Do. In high school, I got bored of it and moved on. Ever since I've just been picking up parts of other forms.
I'm not saying this next line to compare myself to Bruce Lee... rather he is my inspiration. I followed in his footsteps. I never really took any more formal training in other arts like I did in TKD. For him, his foundation was Wing Chun. I learned other arts through mimicry and studying like Bruce Lee.
I have gotten training from friends in other disciplines though so I guess semi-formal? These include Kung Fu (can't tell you what form), western boxing, Muy Thai, and some Jiu Jitsu.
So yea... I guess mixed martial artists is the best definition. I prefer formless though.
Ever do any Jeet Kune Do?